Living Control Systems

Contents

Foreword, Richard S. Marken

ix

Foreword

Some of the best science is done by people who refuse to take the obvious for granted. Copernicus didn't take the sun's daily trek across the sky for granted, Einstein didn't take the regular tick of time for granted, and William T. Powers didn't take the appearance of behavior for granted. The results of not taking things for granted can be powerful new ways of looking at the obvious, but the value of the new point of view is rarely appreciated immediately. Gregor Mendel, who didn't take the blending of hereditary traits for granted, approached the study of heredity in a completely new way, using a combination of botany and mathematics. For his creativity and hard work, having single-handedly invented the field of genetics, he was rewarded with complete and utter neglect. His work was finally recognized 30 years after his death (small comfort to Gregor) by three scientists who independently rediscovered his laws.
Mendel's story illustrates a rule of scientific discovery that is too often followed: "... look at a problem from a totally new angle and people won't so much disagree with you as completely misunderstand you. .They won't grasp what you are talking about and will ignore you." (Maitland A. Edey and Donald C. Johanson, Blueprints, Little, Brown and Co., Boston, Toronto, and London, 1989, p. 105) Powers has looked at the phenomenon of behavior from a totally new angle and, sure enough, people have misunderstood him and ignored him, but they have rarely disagreed with him. The lack of disagreement is rather surprising; since Powers' ideas about behavior contradict the fundamental assumptions of scientific psychology.

<snip>

Richard S. Marken
Los Angeles
July 1989

About Rick Marken

Preface

For uncomfortably close to 30 years I have been writing an article called "Control Theory for the Life Sciences." I have published this article in books and journals, newsletters and proceedings. It has been aimed at behaviorists, cyberneticians, linguists, biologists, social scientists, and anyone else I thought had a glimmer of interest in the subject. I have spoken this article to seminars of graduate students in several disciplines, to medical students, and to faculty members, in classrooms, lecture halls, and brown-bag lunchrooms. You will see the article here, in most of its incarnations. This is getting extremely tiresome, not only for those who have heard the message too many times, but for the one who has heard it the most often of all: me.

This persistence was not in the original plan, which was to communicate the basic theory worked out by R.K. Clark, R.L. McFarland, and myself in the 1950s and published in 1960, then to find a place to work and develop the basic ideas into a full-blown discipline. The theory was so elegant, so close to being self-evident, so clearly useful and explanatory, that neither I nor my collaborators anticipated any problems in gaining support for it. We knew that others were moving in the same general direction and thought they would welcome real signs of progress. I look back now and wonder how we could have predicted the future so poorly.

It is now clear that a new theory is quite welcome in the sciences of life, but only if it does not call for revision of important beliefs. It's all right, for example, to propose a theory saying that an organism's susceptibility to reinforcement by food might be modified by the use of water deprivation. It is not all right to propose a theory that says, in effect, that there is no such thing as reinforcement. There are simply too many scientists who rely on the concept of reinforcement as their main explanation of behavior, the foundation of their theorizing; take away that tool and they have nothing left. The same thing would happen to control theorists if the principles of control were shown to be spurious. Every science needs explanatory principles on which it can rely; if the principles of a science were reorganized yearly, no organized concepts could ever develop. I was naive to think that control theory could become influential in the life sciences over a period of a year or two, or even a decade or two. No idea that can change the course of a science that easily could be anything but a fad. A science cannot change its system concepts overnight, for precisely the same reason that an individual can't do the same thing.

A system concept is an attitude, an understanding, a world view. It's a sense of orderliness and coherence that we see in a body of principles and generalizations. It lives in an individual. It not only forms out of coalescing principles, but it determines which principles belong in the system and which do not. The process is one of assimilation and accommodation, simultaneous mutual adjustment between levels.

Acceptance of control theory requires a change in the beliefs of life scientists at the level of system concepts. System concepts bring order into principles; principles bring order into methods; methods bring order into symbolic representations; symbolic representations bring order into all lower levels of observation. Reorganizing a system concept therefore requires reorganizing everything else. The very way the world looks to us changes when a system concept changes. In fact, the system concept cannot change first. The whole system must reorganize at once. Newcomers to control theory do not all learn it the same way. One part of it is immediately clear to some, other parts to others. What we understand in one area of knowledge causes problems with what we thought we understood in other areas. Even in a willing individual, this reorganization can't take place overnight. It requires years. It requires changes at levels where we all find voluntary change difficult, mysterious, or even impossible.

In the life sciences, there is a widely-accepted system concept of what an organism is. When a scientist speaks from the viewpoint of this system concept, we can recognize it easily, although it's not easy to put into words. The words and descriptions we canfind are only signposts pointing to the system concept. There's a dispassionate aspect to it, a distancing. There's an avoidance of empathy. There's a kind of sternness, an overcoming of natural sympathies, a pride in being immune to the weakness and sentimentality of the layman's view. There's a picture of an organism as a natural object, a bag of chemicals, a preparation of irritable tissue. The word most often used to symbolize this complex structure of attitudes is "objectivity." But objectivity is only evidence of the system concept: the system concept itself is a point of view from which all the rest, from principles on down, hang together and make sense. The system concept is the understanding of living systems that makes objectivity seem appropriate.

The control theory that you will find in this book is a collection of principles, methods, symbol systems, relationships, and observations of more detailed kinds. If I had it to do over again (and if I were a different and smarter person with a better education and a different way of growing up, and understood what I understand now), I would not persist so long in arguing at these levels. I would spend much more time trying to understand and express the difference in system concepts that separates control theory from all conventional theories. Control theory was never the only ingredient in this alternate view of organisms; I only made it seem that way. Even calling it "control theory" is an example of synecdoche, in the sense of referring to something by naming only one of its attributes.

Another important ingredient of this system concept is a view of what constitutes understanding of a system. I do not accept that statistical studies of behavior ever give us understanding of human behavior or human functioning. All they do is overwhelm us with random and unreliable facts. To understand a system, we must be able to see that it must, because of its inner nature, behave as we see it behaving. Its properties must grow out of its inner organization; its behavior must arise from its properties.
This principle is connected to a principle of explanation (or so, from my system concept, it seems). The only kind of explanation I can believe is one that demonstrates the principles that are proposed. It's not enough to say that a block diagram represents a system. One has to show that, in fact, a system organized in that way must behave in a particular way. If you can't deduce how a system would work from the explanation, then you don't have an explanation. The best way to prove that the explanation actually explains something is to cast it as a working simulation, turn it on, and let it operate by the rules you have put in it. If you can't do that, then you don't have a model or an explanation. All you have is more or less persuasive rhetoric.

I did not come down from a mountain with these principles tucked under my arm. They grew out of my training and my occupations, out of my successes and failures, out of my listening to others who were trying to solve the same problems. As the principles changed shape, the system concepts changed shape; as the system concepts changed shape, the principles became clearer. I still don't know how to express very clearly the system concept that contains control theory; now that I know this is needed, I will begin trying to do so. But I have learned that I don't have to provide understanding for others at this level. At best I can make it a little easier. But I don't really have to do it at all.

The reason I don't have to teach system concepts (aside from the fact that I can't) is that people can learn them on their own. The principles and methods of control theory can be taught; once a person grasps them beyond a certain point, they teach themselves. But those principles, everyone discovers, have implications that clash with the rest of one's knowledge of human behavior. Once one has understood an explanation of any one behavior from the standpoint of control theory, other explanations suddenly look different—more evasive and rhetorical, more conjectural, even wrong.

Understanding control theory just as a collection of logical and mathematical manipulations or as a diagram of relationships is relatively easy; those things can be taught to 30 people at once. You can learn those things from this book, reading it from either end. But grasping all the implications of control theory at the higher levels of understanding is hard, and can be done only within one individual at a time. Every control theorist I know has put a great deal at risk in the process of learning this subject. Most of them have suffered the embarrassment of seeing a former belief as foolish or naive, of realizing that they had been uncritical or even gullible. I know of none, however, who would go back to what they believed before, although there is nothing to prevent their doing so—and every encouragement from their colleagues to do just that.

Members of The Control Systems Group conceived the publication of this collection, organized it, and labored to make it real. I am profoundly grateful to them. Seeing all these papers brought together has, unexpectedly, shown me that a phase of my life is over. This book and the fact that I had so little to do with creating it have convinced me that I can stop writing that article over and over. The basic ideas are in good hands; I can let go of them now. Now, perhaps, I can try to remember what was supposed to come next.

William T. Powers
Northbrook, Illinois
July 1989

A Note on the Text

In resetting the text and redrawing the figures of papers included in this volume, I have kept alterations to a minimum (mainly silent corrections of obvious typographical errors and inconsistencies; in particular, the Editor's notes in "Applied Epistemology" were not added by me). The originals must remain as ultimate touchstones, and I alone am responsible for both intended and unintended differences between them and their reproductions herein.

My labors have been eased very significantly by William D. Williams, who arranged to have several of the papers put into computer-readable format, and by my wife Pat, who not only redrew some of the figures, but did so using software she had written herself. I am also grateful for aid from several CSG members and sympathizers, particularly those who helped with bibliographic work, as noted on page 295.

Special thanks are due to copyright holders of the papers reprinted with their generous permission.

Gregory Williams
Gravel Switch, Kentucky
July 1989

[1960, with R.K. Clark and R.L. McFarland]
A General Feedback Theory of Human Behavior:
Part I

Introduction

In this paper we introduce a conceptual model of human behavior, based on some of the fundamental considerations of feedback theory and leading to a generalized theory of behavior. About six years of development lie behind what is presented here, so obviously we cannot explore in this one paper all the ramifications and applications of this theoretical structure which have occurred to us during this period. What we intend to do here is simply to present the theory as concisely as possible, so as to provide a basic paper in the literature to which we can refer when discussing experiments and further theoretical considerations in other papers.

The concepts presented in this paper represent a synthesis of many ideas, some of which have been in print for many years. Indeed, the literature of psychology alone, if interpreted in the light of what is known about feedback control systems, could be used to form the basis for our theory. Our approach did not begin from a psychological orientation but from the physical and mathematical, because the first two authors are physicists, who only after several years of work on this model, began to acquire a more thorough acquaintance with the work of psychologists. Thus, we find it most natural to develop the theoretical model first, before attempting to outline the applications of this model in language appropriate to psychology.

Reproduced with permission of publisher from: Powers, W.T., Clark, R.K, & McFarland, R.L. A general feedback theory of human behavior. Part I Perceptual and Motor Skills, 1960, 11, 71-88.

[1960, with R.K. Clark and R.L. McFarland]
A General Feedback Theory of Human Behavior:
Part II

Introduction

The model described in Part I is only a part of our general theory—the part which organizes our more general ideas about human behavior and human nature. To conceive of human organization as following that of our hierarchical array of FBCS (externally fed back Feedback Control Systems) implies a certain attitude toward behavior, different in some important respects from traditional psychological viewpoints. Some of these differences we began with, but most of them took form only as we went back and forth between modifying our organizational model and observing people behaving.

One of the most puzzling, and in our opinion critical, aspects of human behavior is that behavior appears multiordinal. The same behavior can be described in a number of apparently equally-valid ways, from the particular to the general. Usually this representation of human behavior at varying levels of abstraction is put aside during a scientific study, and one particular level is chosen as the most interesting, or sometimes as the only "proper" one. But for us this multiordinality raised a critical question: is it due to the way in which behavior is observed, or is it somehow a significant property of the behaving system?

The answer we have arrived at is, "Both." One must never forget that the person observing human behavior is a system

Reproduced with permission of publisher from: Powers, W.T., Clark, R.K., & McFarland, RI. A general feedback theory of human behavior: Part II Perceptual and Motor Skills, 1960, 11, 309-323.

[1971]
A Feedback Model for Behavior: Application to a Rat Experiment

Stimulus-response laws can be rendered trivial when environmental feedback exists from R to S. An input quantity (qi), defined as the actual environmental quantity or event that leads to a response, is a function of both the applied stimulus (S) and the feedback from the related ongoing behavior (R): qi = g(h(R, S). The observed behavior is dependent on actual input stimulation via the organism function: R = g(qi). Hence R = g(h(R, S)), and not R = g(S).

Analysis of a shock avoidance experiment done by Verhave illustrates a method for taking environmental feedback effects into account; the resulting model fitted to the behavior of one rat predicts the behavior of another rat in an altered experiment with an RMS error of less than one bar-press per minute. Graphical solutions to a range of possible functions g and h (as above) show why this type of experiment reveals more about the experimental apparatus than about the rats.

When environmental feedback is significant (and negative) one must characterize the organism's actions as behavioral control of stimulation and not stimulus control of behavior.
It has been recognized that the output of an organism, the muscle forces and their consequences which appear as an organism behaves, must influence the inputs, the sensory

Copyright 1971 by the International Society for Systems Sciences. Reprinted with permission from Behavioral Science 16(6), November 1971, 558-563.

[1973]
Feedback: Beyond Behaviorism

Stimulus-response laws
are wholly predictable
within a Control-system model
of behavioral organization.

The basis of scientific psychology is a cause-effect model in which stimuli act on organisms to produce responses. It hardly seems possible that such a simple and venerable model could be in error, but I believe it is. Feedback theory shows in what way the model fails, and what must be done to correct our concepts of organized behavior.

Responses are dependent on present and past stimuli in a way determined by the current organization of the nervous system; that much is too well documented to deny. But it is equally true that stimuli depend on responses according to the current organization of the environment and the body in which the nervous system resides. That fact has been left out of behavioristic analyses of human and animal behavior, largely because most psychologists (especially the most influential early psychologists) have lacked the tool of feedback theory.

Norbert Wiener and later cyberneticists notwithstanding, the full import of feedback in behavioral organization has yet to be realized. The influence of behaviorism, now some 60 years old, is pervasive and subtle. Shaking ourselves free of that viewpoint requires more than learning the terms

Copyright 1973 by the AAAS. Reprinted with permission of the publisher from Science 179(4071), January 26, 1973, 351-356.

[1973, with William M. Baum and Hayne W. Reese]
Behaviorism and Feedback Control

Although there is much of value in the article "Feedback: Beyond behaviorism" by W.T. Powers (26 Jan., p. 351), it is based on an outdated and misconceived idea of behaviorism.

Behaviorism consists in the view that a scientific psychology must deal with the observable. From this proposition, it follows that psychology should be a science of behavior, and that explanations of observed phenomena should be couched in the same terms as the observations themselves, rather than invoking imagined autonomous entities ("explanatory fictions") as causes. Many, perhaps most, psychologists today are behaviorists.

Since its points are mainly methodological, behaviorism never has been wedded to any particular conception of behavior. Early behaviorists perhaps held views similar to the one Powers criticizes, but the inadequacy of describing behavior in terms of responses to stimuli was recognized over 30 years ago. With the recognition that behavior is affected by its consequences (the Law of Effect), open-loop descriptions began to pass away. Few behaviorists today would disagree with Powers's statement, "there can be no nontrivial description of responses to stimuli that leaves out purposes." Emphasis on purpose, in fact, has been the hallmark of modern behaviorists' thinking (1). The behaviorists' solution to the problem of purpose has been exactly the one suggested by Powers—selection by consequences. That behavior and consequences constitute a feedback system is taken as a basic premise (2). It is presented

Copyright 1973 by the AAAS. Reprinted with permission of the publisher from Science 181(4105), September 21,1973,1114,1116,1118-1120.

[1974]
Applied Epistemology

Philosophical investigations sometimes seem divorced from the hard realities of science, which force one to take a position in order to get on with the work at hand. The engineer or physical scientist not engaged in basic research, for example, is almost forced into being a naive realist; one cannot build, design, or analyze an electronic or mechanical device while wondering if the soldering iron, meter, or slide rule is really there.

Once in a while, however, a study that began as a comfortable application of the known to the less well known leads to a philosophical impasse, and one finds himself forced to shift philosophical gears. Perhaps it is a sign of some general paradigm shift that many investigators in many disciplines, even in nuclear physics, are experiencing uncertainty about their working premises, and are beginning to realize that naive realism is not the hard-headed practical man's philosophy it once appeared to be. It may, in fact, create an invitation to illusion.

Other segments in this volume deal in detail with the epistemological position of Piaget, showing dearly that this pioneer has been exploring for years a new concept of knowledge. It may be that Piaget has for several decades suffered an extreme of misunderstanding of his position—or it may be that in his direct approach to the growth of perceptual organization, he has been applying new principles without having organized them into an "official" statement. The subject of this chapter is another approach that has converged to the same

Copyright 1974 by William T. Powers. Reprinted from Charles D. Smock and Ernst von Glasersfeld, eds., Epistemology and Education, 1974, 84-98.

[1976]
The Cybernetic Revolution in Psychology

The picture of a cybernetic model of an organism which I will present in this essay represents what has condensed out of an amorphous cloud which has floated over the United States, Italy, Russia, and England, continuously changing shape but always seeming to gather itself into a more and more definite form. While much is still indefinite, the fundamental principles of a new concept of human and animal nature are now dear. They have nothing to do with automation, man-machine relationships, the study of vast social systems, or the creation of a cybernetically planned political system; some cyberneticists will be as disappointed by that as some psychologists will be relieved. Instead, these principles seem to point in the direction of individual autonomy and freedom, and a level of individual responsibility some might find daunting. I will not pursue such conclusions, however. The main aim here is to present, as dearly as possible, a set of ideas which are likely to cause some of the most fundamental assumptions of behavioral science to be discarded.

Background

Copyright 1976 by the American Society for Cybernetics. Reprinted with permission from ASC Cybernetics Forum 8(3 & 4), Fall/Winter 1974 72-86

[1978]
Quantitative Analysis of Purposive Systems:
Some Spadework at the Foundations of Scientific Psychology

The revolution in psychology that cybernetics at one time seemed to promise has been delayed by four blunders: (a) dismissal of control theory as a mere machine analogy, (b) failure to describe control phenomena from the behaving system's point of view, (c) applying the general control system model with its signals and functions improperly identified, and (d) focusing on man-machine systems in which the "man" part is conventionally described. A general non-linear quasi-static analysis of relationships between an organism and its environment shows that the classical stimulus-response, stimulus-organism-response, or antecedent-consequent analyses of behavioral organization are special cases, a far more likely case being a control system type of relationship. Even for intermittent interactions, the control system equations lead to one simple characterization: Control systems control what they sense, opposing disturbances as they accomplish this end. A series of progressively more complex experimental demonstrations of principle illustrates both phenomena and methodology in a control system approach to the quantitative analysis of purposive systems, that is, systems in which the governing principle is control of input.

This article concerns four old conceptual errors, two mathematical tools (which in this context may be new), and a series of six quantitative experimental demonstrations of principle that begin with a simple engineering-psychology experiment and go well beyond the boundaries of that subdiscipline. My intent is to take a few steps toward a quantitative science of purposive systems.

Copyright 1978 by the American Psychological Association. Reprinted by permission of the publisher from Psychological Review 85(5), September 1978, 417-435.

[1979]
A Cybernetic Model for Research in Human Development

Over the past thirty years, cybernetics has gone in many directions. It is sometimes difficult to see how some modern approaches that go under that name relate to the original concept proposed by Norbert Wiener (1948): the concept that organisms display the characteristics of negative feedback control systems. Since this concept represented the chief revolutionary departure of cybernetics from conventional thinking, one might expect every person claiming to be a cyberneticist to understand the principles of control theory, at least at the level of valid rules of thumb. This is not the case. What most "cyberneticians" do and write is perfectly compatible with traditional models of organisms, and hence is incompatible with the principles of control theory. In this volume, we hope to improve on that state of affairs.

The original promise of a cybernetic revolution in our understanding of human nature can still, I am confident, be realized. To bring it about, however, we must be prepared to change some concepts that have been defended for a long time. We must also be prepared to return for a while to a relatively low level of abstraction, so as to grasp the meaning of control theory in relationship to simple direct experiences. The first step in launching a cybernetic revolution in psychology is to make sure that the fundamental phenomena of control are correctly understood in relationship to behavior.

In this chapter I will be presenting a primer in control theo-

Copyright 1979 by Westview Press. Reprinted with permission of the publisher from Mark N. Ozer, ed., A Cybernetic Approach to the Assessment of Children, 1979,11-66.

[1979]
Degrees of Freedom in Social Interactions

Introduction

Freedom is well-known to be a relative term; one is not free to speak lies to a Grand Jury; one is not free to worship a god that demands human sacrifices; one is not free to publish facsimiles of U.S. currency; and one is not free to choose his domicile from those owned and occupied by others. We are all familiar with the fact that there are different degrees of freedom, none of them absolute.

The term "degrees of freedom" has another meaning, which turns out also to be relevant in this discussion. A physical system is said to have n degrees of freedom if n variables have to be given specific values in order to describe completely the state of the system at a given moment. An object in space has at least six degrees of freedom: three which relate to its location in a three-dimensional coordinate system, and three which relate to its orientation relative to the directions of the coordinate axes. If a system has n degrees of freedom, and all but one of them are specified by being given numerical values, there is only one way left in which the system can change. If the location of an object on a flat surface is specified in terms of an X -Y coordinate system, the only remaining way the object can move is up and down. If the X-position is specified and the height above the plane is specified, the only remaining degree of freedom is in the Y-direction.

Copyright 1979 by Gordon and Breach Science Publishers, Inc. Reprinted with permission of the publisher from Klaus Krippendorff, ed., Communication and Control in Society, 1979, 267-278.

[1986]
On Purpose

The concept of purpose has been in bad repute among life scientists since before they adopted that name. Control theory, on the other hand, shows that the principal property of organismic behavior is its purposiveness. There is clearly a problem of acceptance here, especially because anyone who speaks of purpose in polite scientific company is likely to detect a common reaction—oh, you're one of those. The difficulty is that the word purpose evokes images of mysticism and religious persecution, throwing the whole discussion into the wrong category. It's hard to persuade a scientist to take another look at the phenomenon when he or she is convinced that there isn't any phenomenon.

Copyright 1986 by William T. Powers. Reprinted from Continuing the Conversation (7), Winter 1986,1-3.

[1987]
Control Theory and Cybernetics

In recent CCs, there have been some self-promoting complaints about how unaesthetic we control theorists are. From the receiving end, this is something like getting an obscene phone call: it's hard to think of it as a conversation. Well, I won't put up much of a defense. There are some dull spots to get through on the way to understanding control theory, and a control theorist would be the last person to say anyone has to like control theory, or understand it. On the other hand, if you don't understand control theory, isn't it a little unwise to write thousands of words about what you imagine it to be? I would think that the potential for embarrassment would be reason for caution.

Copyright 1987 by William T. Powers. Reprinted from Continuing the Conversation (11), Winter 1987,13-14

[1988]
The Asymmetry of Control

The circular relationship between organisms and environments is well known: behavior affects the environment and the environment affects behavior. On superficial consideration it may seem that we have a choice: the organism controls its environment, or equally well the environment controls the organism. This is not true.
To see that there is asymmetry in this relationship we can boil the situation down to its simplest elements. In Fig. 1 are two triangles representing agencies. The points are the outputs. The side opposite each point is the input surface, which receives two input effects. One effect is constant the inputs labelled r and d. The other effect is simply the output of the other triangle, labelled respectively p and a. The output a is some constant K times the sum of inputs r and p, and the output p is another constant E times the sum of inputs a and d.

Figure 1.

Copyright 1988 by William T. Powers. Reprinted from Control System Group Newsletter, February 1988, 3.

[1988]
An Outline of Control Theory

Nearly 100 years ago, William James pointed out that organisms differ from every other kind of natural system in one crucial regard: they produce consistent ends by variable means. He made this observation just at the dawn of so-called scientific psychology: his words were quickly forgotten. In their eagerness to make the study of behavior into a science, the American psychologists who became the intellectual leaders of the movement called behaviorism decided to let pure reason govern their approach. In a physical universe, one seeks the LaGrangian: the summing-up of present causes in sufficient detail to allow prediction of future effects. Because the universe is lawful and regular, they reasoned, regularities in behavior must be caused by regular influences on the behaving organism. Thus to predict behavior, all we had to do was study the conditions under which it took place with sufficient precision and care. From such studies would come behavioral laws like the laws of physics. Using these laws the psychologist could then not only predict what behaviors would occur, but by manipulating the environment, control behavior.

From the very beginning, therefore, scientific psychology assumed a property of behavior that is precisely the opposite of the one William James noticed. The psychologists decided that if regularities of behavior occurred, they could be traced back to regular antecedents, and that by manipulating those antecedents they could cause the behaviors to occur again. In

Copyright 1988 by William T. Powers. Reprinted from Conference Workbook for "Texts in Cybernetic Theory," American Society for Cybernetics, Felton, California, October 18-23,1988,1-32.

Published Works by William T. Powers on Living Control Systems, 1957-1988

1957a (with R.L. McFarland and R.K. Clark) "A general feedback theory of human behavior," University of Chicago Counseling Center Discussion Papers 3(18), 21 pp.

1957b (with R.L. McFarland and R.K. Clark) "A general feedback theory of human behavior: A prospectus," American Psychologist 12(7), July, 462.

1960a (with R.K. Clark and R.L. McFarland) "A general feedback theory of human behavior Part I," Perceptual and Motor Skills 11(1), August, 71-88. Reprinted in Ludwig von Bertalanffy and Anatol Rapoport, eds., General Systems: Yearbook of the Society for General Systems Research 5, Society for General Systems Research, Ann Arbor, 1960, 63-73. Reprinted in altered form, as "A general feedback theory of human behavior," in Alfred G. Smith, ed., Communication and Culture Readings in the Codes of Human Interaction, Holt, Rinehart and Winston, New York, et al., 1966, 333-343..

1960b (with R.K. Clark and R.L. McFarland) "A general feedback theory of human behavior. Part II," " Perceptual and Motor Skills 11(3), December, 309-323. Reprinted in Ludwig von Bertalanffy and Anatol Rapoport, eds., General Systems: Yearbook of the Society for General Sys‑

Prepared by Gregory Williams, with help from Mary A. Powers, Richard J. Robertson, Philip J. Runkel„ and Stuart A. Umpleby. Works with italicized dates are reprinted in this volume.